When pipes are joined together or when a connection port of a fluid supply source is connected with a pipe, a pipe joint in accordance with an application is utilized. When, for example, a coolant pipe to allow a coolant of an air conditioner to flow is connected with a connection port of an indoor equipment of an air conditioner or an outdoor equipment thereof, in general, a flare pipe joint in compatible with JIS B 8607 is utilized (see, for example, Patent Literature 1).